In general, piezoelectric actuators are formed from a flat piezoelectric element, which is typically configured to have a specific ratio between the length and the width of the piezoelectric element (the resonator length (L) and width (B) are related by the equation B=0.5 L). This configuration generally enables a plane longitudinal elastic 2-D wave to be excited in the piezoelectric element. The result is generally the linear displacement of the contact point, which is typically located in the center of the resonator and is coupled to the rest of the motor using a contact or friction element attached to the surface of the piezoelectric element.